Immunolocalization of keratins in salivary gland pleomorphic adenoma using monoclonal antibodies

Monoclonal antibodies to keratins (KL1 and PKK1) were tested on paraffin sections in forty cases of pleomorphic adenoma from salivary glands. Squamous cells in the epidermis were positive for KL1, except for the basal cells, which were positive for PKK1. In normal salivary glands, ductal cells were positive for KL1 and PKK1 keratins, whereas KL1 staining of the large excretory ducts was weaker than that of PKK1. Myoepithelial cells were positive only for KL1. In pleomorphic adenoma, the following reactions were noted: a positive staining for KL1 and PKK1 was present in the inner layer of cells within tubular and ductlike structures, a markedly positive staining for KL1 was present in squamous metaplastic cells, and a negative staining reaction with KL1 and PKK1 in spindle-shaped tumor cells was observed within the outer layer. Spindle-shaped or fibroblast-like cells in the stroma, probably myoepithelial in origin, showed an irregular staining expression for KL1 and PKK1.